Hudson had his final IV chemo today. His white cell counts were where they needed to be and everything checked out great. His breathing and his heart sound good. He goes back in three weeks for new chest xrays and to determine the oral chemo protocol we want to follow.
There are two oral chemo protocols out there. Traditionally, vets follow a metronomic protocol. This protocol combines medications (Doxycycline, Rimadyl, Cyclophoshamide and a few others) to work on slowing down the blood supply to cancer cells. By starving the cells, you limit the growth they can achieve. The tumors are not likely to get smaller while on the metronomic regimen, but the point is more to prolong quality of life by preventing or delaying further growth.
The second protocol is only beginning to gain a following. It utilizes Tyrosine Kinase Inhibitors, and combines Palladia, Kinavet and Rimmadyl. Tyrosine kinase inhibitors (TKIs) are a class of chemotheraphy medications that inhibit or block the enzyme tyrosine kinase. Tyrosine Kinase basically acts as an on/off switch for cell replication and growth. this on/off process can become disrupted, often due to a mutated kinase, and actions become unregulated. This can lead to uncontrolled growth and division in the cell, which could lead to cancer. These mutated cells often lead to oncogenes, which are genes that help turn a healthy cell into a cancerous cell. Tyrosine kinase inhibitors treat cancer by correcting this deregulation. How this is done varies depending on the medication. Toceranib (Palladia) inhibits EGFRs (I have no idea what that is), preventing that signal from being stuck “on” and creating uncontrolled proliferation. The gist of tyrosine kinase inhibitors is that they allow for targeted treatment of specific cancers, which lessens the risk of damage to healthy cells and increases treatment success.
TKI's have not been fully proven yet in canines, they are (for giant breeds anyway) four times the cost of the metronomic protocol, and dogs on TKI's are 50% likely to experience severe GI side effects, like vomiting and diarrhea. In contrast, the metronomic protocol has a 20% change of side effects.
Dr. Jansen is going to go over these options with us in detail while Hudson is getting his chest xrays and will provide us an estimate of the cost at that time. Based on what I know so far, I'm honestly leaning toward the metronomic protocol. I freely admit that cost is an aspect for me at this point, but my primary concern is the side effects. Hudson is already 7 ½ years old. Danes typically live 7-10 years. I would LOVE for him to get to 10, but I don’t want him to be miserable on the way there. Traditional IV chemo is given every 2 ½ weeks. Hudson feels a tired and maybe a little nauseous for 2-3 days following chemo, then he gets two weeks of happy healthy days. On oral chemo, he would get pills M/W/F of each week. He’d feel bad virtually all the time. Dr. Janson explained that his dosages could be adjusted to keep him feeling the best possible, but I don’t want the time he has left to be the best possible. On the metronomic protocol, he has the same side effects odds as normal chemo. Normal chemo never really upset his stomach. He never had diarrhea and we can proactively treat for nausea. He was just a little tired.
Dr. Janson said that she is leaning the same way as I am on this one. We can try metronomic first. If after a few months, we notice growth in his tumors, then we can try the TKI’s. Obviously, I’ll be doing a great deal more research on this over the next few weeks.
Hudson's favorite oncology tech came running after us to make sure Hudson got his "graduation" present. J
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